Processes for producing same



Reisaued Apr. 17, 1 951 COLOR. PHOTOGRAPHIC MATERIAL AND PROCESSES FORPRODUCING sAME,

Bela Gaspar, Beverly Hills, Calif.

No Drawing Original No. 2,470,769, dated May 24, 1949, Serial No.537,967, May 29, 1944. Application for reissue May 18, 1950, Serial No.162,828. In Great Britain August 28, 1939 24 Claims. (Cl. 956) Matterenclosed in heavy brackets appears in the original patent but forms nopartfofi this reissue specification; matterprinted in italics indicatesthe additions made by reissue.

1 This application is a continuation in part of my application S. N.354,442, filed August 27, 1940, now abandoned, and relates to improvedphotographic light-sensitive materials in which V at least one of thelight-sensitive emulsions, used j in the form of superposed layers of amultilayer material or in the form of difierently sensitized andiflerently colored emulsion particles distributed within the samelayer, is dyed with an azo dye and to improvements in or relating to theprocess of producing the same. The superposed layers or emulsionparticles, in each instance, form discrete portions within a coating orlayer of the photographic material.

The invention has for its purpose the provision of improved materialwhich can be produced in a very simple and reliable manner and in whichthe dye used for coloring the light-sensitive emulsion has only anegligible tendency to bleed or to diffuse during the manufacture, thestorage or the processing of the material.

It is already known to use water-insoluble dyes for coloring thelight-sensitive emulsions or layers, the insoluble dyes being introducedas such or produced within the colloid from their com-' ponents, by dyesynthesis, or from their soluble derivatives, by decomposition. It isobvious that the coloring of the colloid by means of a soluble dye ismuch simpler than the incorporation of insoluble dyes, it only beingnecessary to add the dye solution to the colloidal solution 01'emulsion. n the other hand, it is a well-known fact that most of thewater soluble azo dyes have a strong tendency to diffuse and that owingto this property it becomes necessary to precipitate the soluble dyewithin the colloid by a precipitating agent. There are only a restrictednumber of soluble dyes available which can be used-Without precipitatingagent, such as, for example, the dyes referred to and used according tomy prior British Patent Specification No. 445,806.

' According to the present invention light-sensitive silver halideemulsions used in the form of superposed layers in a multilayer materialor in the form of differently sensitized and differently coloredparticles are dyed by a water or alkalisoluble polymeric azo dye derivedfrom a diazotized aromatic amino compound which is capable of couplingwith itself, the dye molecule being OH NH 2 formed by such coupling andcontaining a chain wherein a plurality of azo groups are positioned inalternating relationship with radicals of said aromatic compound. It hasbeen found that from low-molecular aromatic components, there can beobtained by coupling of the diazotized aromatic amino compound withitself, dyes which have a high molecular weight and which, on the onehand, are water-soluble but, on the other hand, have only a negligibletendency to bleed or diffuse. Such dyes may readily be employed in thelight-sensitive silver halide emulsions or in dyed filter layersadjacent to a light-sensitive silver halide emulsion layer. Layers dyedaccording to the invention are particularly useful for carrying out theprocess of producing dye images Example 1.--N-(p-aminobenzoyll-H acid(so-' dium salt) is dissolved in water and diazotized by acidifying thesolution with acetic acid and adding sodium nitrite solution. Thediazonium salt'solution is kept at low temperature for about an hour.-Thereafter, sodium carbonate is added to render the solution alkalineand the solution is heated, thereafter, to about 60 C. A'ma-f genta dyeis formed which is salted out 'by' com mon salt. The v dye mayberepresented by the following formula, omitting any terminal groups whichmay bepresent-which discloses ,the char acter of the units going-to makeup the polymeric dye substance: Y Y

scan SOgH or by the formula:

on NB nos 3 in which the portion enclosed by the may be considered an9.20 dye unit. The letter n in both formulae represents an integergreater than one indicating the (main characteristic. wherein aplurality of aZo groups are alternating with radicals of the aromaticcompound. If the high molecular weight polymeric dye as shown in FormulaB is reduced it can readily beseen'howgit will break down to form aproduct of low molecular weight which can be represented H NH EN 00- NH,

110, son

and whose similarity to the units which went to make up the polymericdye,-Formula A, is readily apparent.

For coloring emulsions the dye is dissolved in water and the solution isadded to the light-sensitive emulsion to diffusely distribute the ,dyethroughout the light-sensitive emulsion. For producing filter layers thedye solution is mixed with a gelatin solution which is coated to form afilter layer-on a light-sensitive layer. For coloring light-sensitiveemulsions aboutl-2 grams of the dye are used per sq; m. emulsion layertoobtain .a difi usely dyed layer. Differently colored layers in whichone or more layers are dyed by means of the dyes defined above may becoated in superposition on a common support.

Example 2.- p amino benzoylamino) phenol-2-sulphonic-acid is diazotizedin known manner and to the diazo solution is added 4% ammonia solutionand 5% pyridine. After coupling, the solution is acidified with dilutehydroch 1o ricacid, and the resulting yellow dye is salted out andfiltered. The dye has a good solubility and shows no diffusion ingelatine. About 0.3 to

1.0g. dye can be used per squaremeter coating.

The azo dyes in the above description are large molecules containingseveral azodye units; these azo-dye units alternating with heteronuclearbonds which linksaid azosdye'units together. The following generalformula, omitting anyterminal groups which may be present, representsthe character of the dyes:

where An and Ar: stand for aromatic hetero,- clic. r alip a r dic ap bleof r n azo roups. -.-.-N ..=N- stan s for a a li ka and B for aheteronuclear bond connecting two y un ts.

and where "n represents an integer greater than one. The letter a. meansone,'in the case of the dyes disclosed above. However, I have found thatother values for a are also possible, as will be described in greaterdetail. The expression heteronuclear bond means a chemical linkageinterrupting the system of conjugation, and, therefore, practicallyexcluding any essential influence of a dye unit (or groups within such adye unit) on the color characteristics of any one of the other azo-dyeunits beyond the bridge B. The expression azo-dye unit" means that partof the molecule limited by two heteronuclear bonds (or by one bond if itis a terminal group) and which determines the spectral qualities of thedye. If

a dye of the indicated formula (where a equals,

is formed. The size of this reduction product depends only on the sizeof the single components and is independent of the value for n; in theoriginal dye. The reduction product of a nondiifusing high molecular dyeof the indicated formula is, therefore, easily removable from aphotographic colloid by washing.

It has been found the polymeric dyes prepared in other ways thandescribed above have the same advantages and serve as well forcoloration of photographic. colloids; particularly silver halideemulsions'containing gelatine, or other watersoluble or water-permeablecolloids, such as methyl cellulose or cellulose glycolic acid, polymericvinyl derivatives, and other colloids used for multilayer colorphotographic materials wherebyin each differently sensitized silverhalide layer a differently colored dye is incorporated.

The dyes, according to the invention, are'represented by the samegeneral formula given above; the new dyes may contain identical orunidentical dye units, and every single dye unit itself may contain oneor more azo groups. The number of units, n, is determined orundetermined. In order to clarify the objects of the invention, adetailed description and further definitions are given as follows:

1. The dye unit Any low molecular weight azo dye which is capable ofbeing linked to other (identical or .unidentical) azo dyes by aheteronuclear bond is a dye unit according to the definition of thepresent true disazo dye a becomes two, and in a trisazodye:a" assumesthe valueof three. A polymeric pol'yazo dye (a l and n 1 in the generalformula) upon reduction gives n(a-1) molecules of the formula,

NHz-Arr-NHz and n-1 molecules of the formula NHzArz-B 'Ar1,NI-I2 Iexclusive of the terminal molecules all of which are easily removablefrom the photographic colloid, independently of the polymeric grade n ofthe original dye.

2. The combination of dye units The dye units, linked together by aheteronuclear bond are, in the simplest case, identical.- However, theymay be different as well. These difierent dye units linked together canbe of iden tical or different coloration; one azo-dye unit may be amonoazo dye and the next azo-dye unit may bea polyazo dye. It is,therefore, possible to combine different yellow, magenta, orblue-greenazodye units to form yellow, magenta, red, cyan, violet, green or blackdyes.

a. The heteronuclear bond The dye units contained in the polymeric dye ae @14 y a Qarboa to carbon linkage or by any bridge formed bysubstituted carbon atoms or hetero-atoms, such as, for example,ArO-, O-,S, SO2, CO, NHCO--, alkylene, arylene, -O-alkylene-O-, OaryleneO-, E,NH--CONH,

Ar-CO--, SO2NH, -NH-X-NH-, and NHY-NH wherein X is the divalent radicalof a dibasic organic acid and Y. is a bivalent hydrocarbon residue. Anyredical is suitable provided that it interrupts the conjugation of thechain, and that it does not increase the molecular weight or decreasethe solubility of the resulting reduction project to such an extent thatit will prevent the removal or dissolution of the product from thephotographic layer.

4. substituents within the dye units The dye units may contain one ormore solubilizing groups such as, for example, sulphonic or carboxylicacid groups which make them water soluble either in the free acid formor in the form of salts; or they might contain group which facilitatetheir solubility in organic solvents, or both in water and organicsolvents, or in a mixture of water and organic solvents. Such groups arehydroxyalkyl groups, polyhydroxyalkyl groups, hydroxy-amino-alkyl,quaternary amino groups, and many other substituents. According to theinvention the solubility properties of the dyes are selected only withrespect to the most suitable solvent for a chosen photographic colloidsince they have, in spite of their great solubility, no tendency towarddiffusion, and, furthermore, after reduction they form low molecularWeight reduction products which can be easily removed from aphotographic colloid by washing, or which go into solution alreadyduring the reduction of the polymeric azo dye. Up to now it has beenconsidered necessary to use dyes which contained only a minimum numberof solubilizing groups; or to increase the molecular weight of solubledyes byattaching substituents such as long chain fatty acid derivaties,or other high molecular weight substituents which reduce the solubilityof the dyes or which prevent the easy or complete removal of thereduction products, thereby affecting the whites of the resultingphotographic dye images. Another disadvantage of such methods consistsin too low a tinctorial power of the dyes weighted by high molecularsubstituents so that to reach the necessary dye densities, a too largequantity of dye has to be used.

5. The polymeric grade n It depends on the methods of synthesis chosenif the polymeric grade n is determined or undetermined.

The coupling of a polydiazo compound with a coupling compound having twoor more coupling positions yields a polymeric azo dye where n is largebut not determined. Another method to synthesize polymeric dyes of largebut undetermined molecular size consists in connecting monoazo, disazo,trisazo, or polyazo dyes, which have reactive groups in the terminalgroups, with a bivalent reagent to link the single dyes into a polymericazo dye of a larger molecule.

The synthesis of dyes having a determined molecular size can beperformed; i. e., by coupling a diazo or tetrazo compound with acoupling compound which contains an amino group careaching a suitablesize of molecule.

equal or similar 'coupling compound. This operation is repeated as'oftenas necessary to obtain a polymeric azo dye of sufliciently largemolecular weight. After each operation a diffusion test is made and anon-diifusing dye results after The number of dye units required toreach a dye stable to diffusion varies with the chemical properties ofthe coupling compound and also with the properties of the photographiccolloids used, and can be easily determined by simple diffusion testsfor each dye. The diffusion test may be carried out, for example, in thefollowing manner, i. e., a quantity of colorless 5 to 10 per centgelatine or other photographic colloid solution is coated on a base suchas celluloid film or glass plate and dried. A second coating is placedon top of this clear coating, using the same concentration of colloid towhich a solution of the dye has been added in suiflcient quantity toreach the desired dye density. After drying, the material is soaked inwater, and the upper layer is removed with a sharp instrument, and thelower clear layer examined for evidence of diffusion. In most cases thematerial is carried through a sequence of photographic processing bathssuch as the depable of further diazotation andby diazotizing t theresulting amino-azo dye and coupling with an veloper, fixing bath, dyebleach, etc., and after final washing the dyed layer is removed and thelower clear layer examined for evidence of diffusion.

The polymeric grade n required to render the dye stable towardsdiffusion is inversely proportional to the number a of azo groups withinone azo-dye unit. I have found that the product a n must be greater thantwo in order to prevent diffusion of the dyes in the processing baths.However, a higher polymeric degree than the minimum degree is preferableand does not adversely affect the solubility and tinctorial power of thedye nor the molecular size of the reduction products of the dye.

The above mentioned general methods are illustrated by the followingspecific examples. There are, of course, many forms of the inventionother than described in these specific examples.

Example 3.9.3 grams of aniline are diazotized and coupled in knownmanner with 22 grams of l [4 amino phenyl] 5 pyrazolone 3 carbonic acid(Beilstein, Handbuch der Organischen Chemie, 4th ed., supplementary vol.XXV, page 568) in sodium carbonate solution. After completion of thecoupling the resulting dye is salted out, filtered off, washed anddissolved in water 6.9 grams of sodium nitrite are added to the dyesolution which is then poured into 35 ml. of hydrochloric acid (D=l.19)diluted with ice water. After stirring at a temperature below 6 C. for 1hour the resulting diazo compound is stirred into a solution of 22 gramsof sodium carbonate and 22 grams of 1-[4-amino-phenyl]-5-pyrazolone-3-carbonic acid in 1 liter of water which contains 10% pyridine, and themixture is kept at a temperature of 8 C. After stirring for an hour, thesolution is heated, acidified with hydrochloric acid, and the dye isprecipitated, filtered and washed with dilute hydrochloric acid. The dyeis again diazotized and coupled'with the same quantity of l[4-amino-phenyl] -5 -pyrazo1one-3- carbonic acid, as described above,and the resulting dye is precipitated, with dilute hydrochloric "'acid.The-dye, when tested for diffusion, shows with most gelatines only aslight diffusion When two further diazotizations and couplings areperformed in the same way as described above no ease? I difiusion occurswith the resulting dye. The dye bonate. Hereby y fl azo dye is obtained;is believed to have the following formula: the monoazo dye units ofwhich are connected by coon 7 COOH r =N J=N C N=N- -o \N-C -N=N- o NONH,ownf lm \O(OH) where m stands for either two *or four. Am ethylenebridge.

In the above example the aniline can be replaced with 12.'7 grams ofchloro-aniline or 17.3 grams of metanilic acid. Furthermore in any or inall of the couplings the 1-[4-amino-phenyl] -5 pyrazolone-3-carbonic.acid can be replaced by other 'azo couplers, for instance, byS-(p-aminobenzoylamino) phenol-2-sulphonic acid.

Example 4.15 grams of acetyl-p-phenylendie-mine are diazotized andcoupled in known manner in sodium carbonate solution with 22 grams ofl-[4-amino-phenyl]-5-pyrazolone-3- carbonic acid. The dye is salted out,filtered off, dissolved in water and boiled with a 5% potassiumhydroxide solution in order to split off the acetyl group. Thereafterthe dye is salted out,

Example 6.34.4 grams of benzidine-2,2-disulfonic acid are tetrazotizedand coupled with 53.4 grams of 1.1-[2.2-disulpho-diphenylene- (4.4)l-bis-(5-pyrazolone-3-carbonic acid) (Bellstein, l. c.) in a coldaqueous solution of 10% pyridine. The yellow dye is precipitated withdilute hydrochloric acid solution, filtered off, and washed withalcohol. The dye, neutralized with 16.4 grams of sodium carbonate, formsa yellow solution in water which is ready for addition to a photographiccolloid. For color photographic or filter purposes 0.3 to 1 gram of thedye is used per square meter. The photographic layers dyed with this dyeare entirely free of diffusion. The probable structure of the dye isCOOH 03H SOK filtered 011, and dissolved in a sodium carbonate solution.Phosgene gas is introduced under cooling and stirring, whereby apolymeric azo dye is formed in which the dye units COOH The same dye isobtained by tet'razotizing 24.2 grams of diamino-diphenylurea. andcoupling the same in a 20% pyridine solution with 26.8 grams of.carbonyl-bis-l- (4-amino-phenyl) -5-pyrazolone-3-carbonic acid.

Example 5.Instead of reacting the monoazo dye described in the foregoingexample with phosgene, other acid chlorides derived from polyvalentacids, such as succinyl chloride, can be used: 33.9 grams of the monoazodye described in Example 4 are dissolved in anhydrous pyridine, and 15.5grams of succinyl chloride are'stirred in small portions into the cooledsolution. Half an hour after the addition of the chloride is completed,the temperature is raised to 50 C. and kept at this temperature for 1hour. The dye is finally precipitated by adding, under cooling, dilutehydrochloric acid. After filtering ofi the dye is dissolved in sodiumcarbonate solution and purified by reprecipitation with acid. Apolymeric yellow a'zo dye results in which the monoazo dye units arelinked together with groups. A further variation consists in treatingthe monoazo dye of the Example 4 with 18.8 grams of ethylene bromide at90 C. under reflux in dioxane in the presence of calcium car- OH NH;

so. slow no. 80m Ho-s [soar no.

chloric acid solution in known manner.

The isomer dye having the sulphonic'acid groups attached in the3,3'-position (instead of the 2,2- position) of the diphenylene radicalshas a simi'-' lar shade.

Example 7.-a. 34.4 grams of benzidine-2,2' disulphonic acid aretetrazotized in dilute hydro- To this tetrazo solution, a solutioncontaining 31.9 grams of H-acid, 8.3 grams of sodium acetate and 6 ml.of acetic acid is added slowly while stirring. The temperature is keptat 5 C. for 2 hours. A bluishred monoazo dye forms. Thereafter about ml.of pyridine are added whereby the bluish-red monoazo dye transforms intoa blue-green polymeric dye. After 1 hour the solution is acidified withan excess of hydrochloric acid, and the polymeric blue-green azo dyeprecipitatesin amorphous form. The liquid is decanted and theprecipitate washed with 5% sodium chloride solution. For purification,the dye is dissolved in aqueous sodium carbonate solution, salted out,filtered and Washed'with 5% sodium chloride'sO lution.

b. A dye similar to that described in Example 79. is obtained by thefollowing procedure: 34.4 grams of benzidin'e-2,2-disulphonic acid aretetrazotized in hydrochloric acid solution. To this terraazo solution, asolution containing 63.8 grams of H-acid, 16.6 grams of sodium acetate,and 12 ml. of acetic acid is added in the same way as in Example 72..After standing for two hours, to this solution which contains a magentadisazo dye, a tetraazo solution prepared with 34.4 grams ofbenzidine-disulphonic acid and 160. ml. of pyridine is added whereby ablue-green dye is' formed which is isolated and purified as in Example7a. p

The probable formula of the dye formed in Example a is I 'and theprobable formula 01" the dye formed in Example b is:

OH NH;

Ems a dog: H035 aniline-2* sulfonic acid withl-amino-napbthale'ne-7esulfonic acid, diazotizing the resulting The dyesare well soluble in water and their 10 monoazo dye and coupling it with1-amino-2- gelatine coatings are free of diffusion into adjacentgelatine layers.

Instead of the tetrazotized benzidine -2,2-di- :sulphonic acid in theforegoing examples, a number of other tetrazo compounds may be used withequal success, such as for example; tetrazotizeddiaminodiphenylsulphone, diaminodiphenylsulphone-sulfonic acid,diaminodiphenylsulphone-disulphonic acid, dianisidine,diaminodiphenylmethane, diaminodibenzyl, diaminobenzophenone,diaminodiphenyl-sulphide, or diaminodiphenyl ether. The aforementionedcompounds might contain further substituents such as alkoxy, alkyl,oxyalkyl groups or halogens.

Example 8.-33.1 grams of 3,3-diamino-4,4'- dimethoxy-diphenylmethanechlorohydrate are tetrazotized in known manner and coupled in 5%pyridine solutionwith 107.6 grams of p-amino-benzoyl-H-acid. The diaminodisazo dye is precipitated with hydrochloric acid and sodium chloride,filtered off, dissolved in water and tetrazotized in acid solution with13.8 grams of sodium nitrite and coupled with 107.6 grams of "dyes ineach step by dissolving and reprecipitating them. The final product is amagenta hexazo dye which is believed to have the following formula:

NH 0H Bo s The dye has a good solubility in water and is added to agelatine silver bromide emulsion in a quantity of 0.5 to 1 gram persquaremeter. It

doesv not diffuse into adjacent gelatine layers.

In the above example in place of 3,3-diamino-4,4-dimethoxy-diphenylmethane many other diamino aryl compounds such asp-diaminodi- ,phenyl ether, 2, 2'-dichlorobenzidine, ordiaminodiphenylurea can be used. The p-aminobenzoyl- ,I-I-acid can besubstituted in one, two, or all coupling steps withaminoanisolsulfo-H-acid or aminobenzoyl-K-acid. Furthermore, the lastcoupling can be made with a coupling compound, which is free ofdiazotizable amino groups, such as p-toluenesulfo-H-acid ordichlorobenzyl-K- acid.

Example 9.'-.-A trisazo dye is made in known manner bycouplingdiazotized 4-oxalylaminomethoxynaphthalene 6 sulphonic acid.This dye is then diazotized and coupled in pyridine and ammonia with2-amino-5-naphthol-7-sulfonic acid. The making of similar trisazo dyesis described in the U. S. Patent No. 1,602,991. The resulting trisazodye is dissolved, and the oxalyl group is split off with cold 5% sodiumhydroxide solution. Thereafter, the dye is salted out, filtered oil,dissolved in a sodium carbonate pyridine 20 solution and treated withphosgene gas. A blue- SOaH 01H formed by a plurality of identical lowmolecular weight members Ar N= N, wherein Ar stands for a group whichhas both a coupling position 'and at least one salt-forming substituentand comprises an aromatic radical capable of carrying an azo group, nstands for an integer greater OCH;

than one, said members ArN=N being linked together by the azo group ofone member being oofattached to the coupling position of the nextmember.

2. A photographic material comprising two superposed colloid layers, atleast one of the layers being a light sensitive silver halide emuls ionlayer comprising a high molecular weight "dye-which is soluble in asubstance selected from the group consisting of water and aqueous alkaliand which includes the following general structure (ArN=N)n formed by aplurality of identical low molecular 'weight'members Ar-N=N, wherein Arstands for a group which has bothacoupling position and at least onesalt forming substituent and cam comprises an aromatic radical capableof carry ing an .azo group, n stands tor an integer greater than one,said members Ar N=N being linked together by the azo group of one memberbeing attached to the coupling position of the next member. I I

3. A photographic material comprising a lightsensitive silver halideemulsion and a high inolecular weight dye in the presence of said silverhalide which dye is soluble in a substance-selected from the group ofsubstances consisting of water and aqueous amau and includes thefollowing general structure formed by a'pluralit'y of identical lowmolecular weight members AI'N=N, wherein Ar stands for a group which hasboth a coupling position and at least one salt-forming substituent and"comprises an aromatic radical capable of carrying an azo group, "nstands for an integer greater than one, said members Ar N='N beinglinked together by the azo group of one member being attached to thecoupling position of the next member.

4. A photographic material having a layer comprising a light-sensitivesilver halide emulsion and a high'molecular weight dye which is solublein a substance selected from the group of substances consisting of Waterand aqueous alkali and which includes the following general structureformed by a plurality of identical low molecular weight members ArN=N,wherein Ar stands for a group which has :both a coupling position and atleast one salt-forming 'substituent and comprises an aromatic radicalcapable of carrying an azo group ,n stands for an integer greater thanone, said members ArN=N being linked together by the azo group of onemember being attached to the coupling position of the next member.

, 5. A process for producing a coloredphotographic material comprisingat least two superposed colloid layers, at least one of said layersbeing a light sensitive silver halide layer and at least one of saidlayers being a colored colloid layer, which comprises coloring thecolloid used for the production of said colored colloid layer with asoluble high molecular weight dye which includes the following generalstructure (--AI--N=N)n formed by a plurality of identical low molecularweight members Ar--N=N, wherein Ar stands tor, a group which has both acoupling position and at least one salt-forming substituent andcomprises an aromatic radical capable of carrying an azo group, n standsfor aninteger greater than one, said members ArN=N beinglinked togetherby the azo group of one member being attached to the coupling positionof the next formed by a plurality of identical low molecular weightmembers Ar-N=N, wherein Ar stands for a group which has both a couplingposition and at least one salt-forming substituent and comprises anaromatic radical capable of carrying an azo group, "n stands for aninteger greater than one, said members ArN=N being linked together bythe azo group of one member being attached to the coupling position ofthe next member. s

- 7. A process for producing a colored photographic image in aphotographic material comprising a plurality of colloid layers, at leastone of said layers containing a silver image and at least one of saidlayers being diffusely dyed with a soluble high'molecular weight dyewhich includes the following general structure (Ar--N N)n formed by aplurality of identical low molecular weight members Ar--N=N, wherein Arstands for a group Whichhas both a coupling position and at least onesalt-forming substituent and comprises an aromatic radical capable ofcarrying an azo group, n stands for an integer greater than one, saidmembers ArN=N being linked together by the azo group of one member beingattached to the coupling position of the next member which comprisestreating said material to locally destroy by reducion said dye in thepresence of said silver image and washing said material.

8. A process for producing a colored image in colored photographiccolloid layer containing a silver image, said layer being diffusely dyedwith a soluble high molecular weight dye which includes the followinggeneral structure formed by a. plurality of identical low molecularWeight members ArN =N, wherein Ar stands for a group which has both acoupling position and 1 at least one salt-forming substituent andcomprises an aromatic radical capable of carrying an azo group, n standsfor an integer greater than one, said members Ar -N N being linkedtogether by the azo group of one member being attached to the couplingposition "of the next member which comprises treating said material tolocally destroy by reduction said dye in the presence of said silverimage and washing said material.

9. A process for producing a colored image in a colored photographiccolloid layer containing a silver image, said layer being diffusely dyedwith a soluble high molecular weight dye which includes the followinggeneral structure:

formed by a plurality of identical low molecular weight members A'r- N-N, whereinA'r stands for a group which has both a coupling position andat least one salt -forming substituent and comprises an aromatic radicalcapable of carrying an azo group "n stands for aninteger greater thanone, said members Ar N=N being linked together by the azo group of onemember being attached to the coupling position of the next member, whichcomprises treating said material to locally destroy by reduction saiddye in the presence ofsaid silver image and removing the dye reductionproducts "from said layer by washing.

10. A photographic material comprising at least two superposed colloidlayers, at least one of the layers being a light sensitive silver halideemuh 13 Bionlayer and at least one layer comprising a soluble highmolecular weight dye which carries at least one solubilizin group andincludes the following general structure:

formed by a plurality of low molecular weight members -B (-A11N=N-) aA12wherein An and Arzstand for a. group comprising a-radical selected fromthe class consisting of aromatic, heterocyclic and aliphatic radicals, Bstands for a heteronuclear bond, n stands for an integer greater thanone and a stands for an integer from one to four and the product of aand n is greater than two.

11. A photographic material comprising at least two superposed colloidlayers, at least one of the layers being a light sensitive silver halideemulsion layer and at least one layer comprising a soluble highmolecular weight dye which carries at least one solubilizing group andincludes the following general structure:

formed by a plurality of low molecular weight members wherein AI'l andAlz stand for a group comprising a radical selected from the classconsisting of aromatic, heterocyclic and aliphatic radicals capable ofcarrying an azo group, B stands for a heteronuclear bond, n stands foran integer greater than one and 2. stands for an integer from one tofour and the product of a and n is greater than two.

12. A photographic material comprising at least two superposed colloidlayers, at least one of the layers being a light sensitive silver halideemulsion layer and at least one layer comprising a soluble highmolecular weight dye which carries at least one solubilizing group andincludes the following general structure:

formed by a plurality of identical low molecular weight members whereinAI'l and Arz stand for a group comprising a radical selected from theclass consisting of aromatic, heterocyclic and aliphatic radicals, Bstands for a heteronuclear bond, n stands for an integer greater thanone and a stands for an integer from one to four and the product of aand n is greater than two.

13. A photographic material comprising at least two superposed colloidlayers, at least one of the layers being a light sensitive silver halideemulsion layer and at least one layer comprising a soluble highmolecular weight dye which carries at least one solubilizing group andincludes the following general structure:

formed by a plurality of diiierently colored low molecular weightmembers wherein An and Ari stand for a roup comprising a radicalselected from the class consisting of aromatic, heterocyclic andaliphatic radicals, B stands for a heteronuclear bond, n stands for aninteger greater thanone and astands for an integer from one tofour; andthe product of *a andformed by a plurality of identical low molecularweight members wherein An and Arc stand for a group comprising a radicalselected from the class consisting of aromatic, heterocyclic andaliphatic radicals capable of carrying an 2.20 group, B stands for aheteronuclear bond, 11 stands for an integer greater than one and astands for an integer from one to four and the product of a and n isgreater than two.

15. A photographic material comprising at least two superposed colloidlayers, at least one: of the layers being a light sensitive silverhalide emulsion layer and at least one layer comprising: a soluble highmolecular Weight dye which carries" at least one solubilizing group andincludes the:

following general structure:

[-B(A1'1-N=N) aAIZ-Jn formed by a plurality ofdifierently colored low'molecular weight members 13 (Al1 N=N) aAI'Z wherein Al'l and An standfor a group compris-- ing a radical selected from the class consistingof aromatic, heterocyclic and aliphatic radicalscapable of carrying anazo group, B stands for a. heteronuclear bond, n stands for an integergreater than one and a stands for an integerfrom one to four and theproduct of a and n is greater than two.

16. A photographic material comprising at least two superposed colloidlayers, at least one: of the layers being a light sensitive silverhalide. emulsion layer and at least one layer comprising: a soluble highmolecular weight azo dye formed? by a chain which contains at least four,low' molecular weight members, each carrying at least; one azo groupand at least one heteronuclear bond. linking together said members, thenumber oft said heteronuclear bonds multiplied by the humber of azogroups conjugated with each other giving a product which is greater thantwo.

17. A photographic material comprising at least two superposed colloidlayers, at least one of the layers being a light sensitive silver halideemulsion layer and at least one layer comprising a soluble highmolecular weight dye which carries at least one solubilizing group andincludes the following general structure:

[B(AI'1N=N)aAI'2-]n formed by a plurality of low molecular weightmembers -13 Ari--N=N) aAI'2-- wherein An and Ara stand for a groupcomprising a radical selected from the class consisting of aromatic,heterocyclic and aliphatic radicals capable of carrying an azo group, Bstands for a heteronuclear bond which in at least one low molecularweight member of the series. comprises the group -CO-NH-, "n stands foran integer 18 greater than one and 'a-" stands for an integer: from oneto four and the product of a and "11 is greater than two.

18. A photographic material comprising at least two superposed colloidlayers, at least one of the layers being a light sensitive silver halideemulsion layer and at least one layer comprising a soluble highmolecular weight dye which carries at least one solubilizing' group andincludes the following general structure:

formed by a plurality of low molecular weight members B(A1:1N=N)aAr2whereinAn and Arz. standior a group comprisins a radical selectedv fromthe class consisting of aromatic heterocyclic and. aliphatic; radicalscapable of. carrying an azo-group, B stands for a heteronuclear bondwhich in at least one low molecular Weightmember of the series comprisesthe group SO2NH, n stands for an integer greater. thanv one and 2.stands for an integer from one to four and the product of a and n isgreater than two.

19;. A photographic material comprising at least two superposed colloid.layers, at least one of the, layers being a lightsensi-tivesilver.halide, emulsion layer and atleast one layer comprising a soluble highmolecular weight dye which carries at least one solubilizing group andincludes the following general structure:

formed by a plurality oflow molecular weight members, 7

B(-Ar1-N=N) aAr2 wherein An and Ar2= stand for agroup comprising' aradical selectedfrom the class consisting of aromatic, heterocyclic andaliphatic radicals capable of carrying an azo group; B stands for aheteronuclear bond which in at least one low molecular weight member ofthe series comprises the group -NHXNH- wherein X is the divalent radicalof a dibasic organic acid, n stands for an integer greater than on'e anda stands for an integer from" one to' four and the product of a and n isgreater than two.

20. A photographic material including'a support and a coating on saidsupport, said coating comprising a plurality of discrete portions, atleast one of said discrete portionscontaining a light sensitive silverhalide emulsion and at least one of said discrete portions containing asoluble mm-difiusing high molecular weight dye which carries at leastone solubilizinggroup and includes the following general structureformed by a plurality of low? molecular weight. members B(Ar1N=N )aArzwherein ATI and Arz stand for a group comprising a radical selected fromthe'class consisting: of aromatic, heterocyclic and aliphatic radicalscapable of carryingan-azo group; B stamis for a heteronuclear bond, nistands for an integer greater than one. and.a stands-for aninteger from:one to four and the product of. a and n is greater than two.

21. Avphotographic materiallcomprising a light sensitive silver halideemulsion and-ahighmolecular weight dyeinthepresence of said silver1241-- new lide when dye carries at least one solubilieing group andincludes the following general struc ture aAT2]n formed by a pluralityof low molecular weigh members wherein Ari andiArz stand for a groupcomprising a radical selected from the class consisting of aromatic,heterocyclicand aliphaticradical'scapable of carrying an azogroup, 3stands for a hetieronuclear bond, n stands for an integer greater thanone. and- "a stands, for an integer from one to four and the product ofa and n is greater than two. H

22'. Arphotographie material comprising a light sensitive silver halideemulsion and a high melee-=- ular weight dye in the presence of saidsilver ha lide which dye carries at least one SOZ'LLbiZiaing group andincludes the following general struc-- ture formed by" a plurality oflow molecular weight members wherein AM. and A12 standfor a groupcomprising a radical selected from the class: consisting of aromatic,heterocyclic and aliphatic radicals capable of carrying; an azogroup;.B' stands tor a; heteronuclear bond which in at least onelourmolecular weight member of the series comprises: the group --C'ONH-, n stands for an: integer greater than one and astandsjoranintege-r from one to four and: the product of a and "n. isgreater than; two.

23-; A photographicmaterial comprisinaalight sensitive; silverhalidee'mulsion and a high melee-'- ular weight dye: in the pres'ence ofsaid si'luer ha--' lide' dye carries: at" least one solubilizinggroupand includes: the ,tollowing general. struc ture formed by a pluralityof low molecularweig'ht members wherein-Ariana A'rz stands-for a groupcompris ing a radical selected from the classconsistin'g of aromatic,heterocyclic' and aliphatic radicals c'apableoi-carrying in ace group;nuanceora heteronucleanbond which in at least one lowmo lecular weightmember of the series comprises the group'SOzNH, stands'for an integergreater than one and a standsfor an integer from one to fouran-dth'e'product of a. and" is greater than two.

24'. A photographic material comprisinga light sensitive silver halide"emulsion and a" mo; lecular weight dye in the presence of said silverhalide which dye carries at least one solubilizing group and'includesthe following general structure. 1 V

17 of aromatic, heterocyclic and aliphatic radicals capable of carryingan azo group, B stands for a heteronuclear bond which in at least onelow molecular weight member of the series comprises i the group -NH-XNH-wherein X is the divalent radical of a dibasic organic acid, n

stands for an integer greater than one and a stands for an integer fromone to four and the product of a and "n is greater than two.

BELA GASPAR.

REFERENCES CITED The following references are of record in the file ofthis patent or the original patent:

Gaspar Oct. 31, 1939 Number Number Name Date Gaspar Apr. 28, 1942Chechak June 16, 1942 Seymour June 16, 1942 Carroll et a1. Sept. 8, 1942Carroll et a1 Sept. 8, 1942 .Woodward Feb. 2 1944 Allen et a1 Apr. 11,1944 FOREIGN PATENTS Country Date Great Britain Apr. 30, 1925 FranceDec. 28, 1937 Great Britain Nov. 30, 1938 Switzerland Aug. 1,1939 GreatBritain Nov. 12, 1941 Great Britain Nov. 10, 1942 Great Britain Feb. 25,1943 Great Britain Feb. 25, 1943

